Securities and Exchange Commission chairman Mary Schapiro said that the creation of a system for capturing all stock market data in close to real time is likely half as much as the $4 billion originally estimated.

Speaking to the Senate Permanent Subcommittee on Investigations and the Senate Banking Subcommittee on Securities, Schapiro said the costs of setting up the system for creating a consolidated audit trail of volume, price and parties involved in stock market transactions can be sliced dramatically by using existing systems in the industry, as a starting point, the Dow Jones newswire reported.

The comment and estimate comes weeks after representatives of the New York Stock Exchange, the Nasdaq OMX Group and the Financial Industry Regulatory Authority all urged the Securities and Exchange Commission to base the construction of the audit trail on existing systems at a meeting in New York, as reported by Securities Technology Monitor.

The trail of choice for the industry executives appearing on a panel at the Capital Markets Consortium meeting in Hanover Square was FINRA’s existing Order Audit Trail System, known as OATS.

“Let’s use the existing systems which should allow us to get off the ground quickly,’’ said Claudia Crowley the chief executive officer of the NYSE Regulation arm of NYSE Euronext.

The SEC originally estimated would cost the industry $4.1 billion upfront to build and $2 billion a year to maintain and operate.

Schapiro on Wednesday said the project could be sped up and costs cut perhaps in half, if it relied on existing systems.

"We believe that we can dramatically reduce the costs and the timetable for implementation," she said, according to Dow JOnes.

Schapiro said the SEC no longer expects brokers will have to create new reporting systems from scratch. The cost of such systems accounted for from between 50% and 80% of the original cost estimate, she said, according to the Dow Jones report.